The suicide or homicide bomber has been identified as the one threat that is virtually unstoppable. The thinking of the bomber defies all societal norms. With that being said, the logical solution to the problem would be the development of a means for detecting the bomber at a safe distance from a potential target. To date, there are no known concealed weapons or explosive detection systems available that purport to detect a concealed weapon (or weapons) or explosive devices from a distance of more than 20 yards. Reference is made to an article in the July 2002 Discover Magazine entitled “Beyond X-ray Vision” by Ivan Amato for a recent survey of the current state of the technology. Attention is also called to an article in the fall 1998 The Bridge published by the National Academy of Sciences entitled “Preventing Aircraft Bombings” by Lyle Malotky and Sandra Hyland for additional background information on the problem to be solved.
Almost every known detection system is electromagnetic based and requires an individual to pass through a fixed passageway. When metallic objects pass through the passageway, a warning signal is activated because a change in magnetic flux is detected. This type of system either detects or does not detect a metal object and makes no determination relative to the amount of metal present. Keys, jewelry, watches, and metal-framed eyeglasses may all trigger such a system.
U.S. Pat. No. 6,359,582 describes a weapons detector and method utilizing Radar in conjunction with stored spectral signatures. The system is said to be capable of measuring the self-resonant frequencies of weaponry. It is claimed that accuracies of greater than 98% can be obtained at distances, preferably between 4-15 yards. It is also claimed to be capable of detecting metal and non-metal weapons on a human body, in purses, briefcases and under clothing and discerning from objects such as belt buckles, coins, keys, calculators and cellular phones. This system has the disadvantage of relying on the presence of unique spectral signatures, which must be pre-stored or learned by a computer employing artificial intelligence techniques.
Another patent, U.S. Pat. No. 6,243,036, titled Signal Processing for Object Detection System describes another concealed weapon detection system. The patent describes detecting concealed weapons by calculating the difference of a pair of differences between levels of different polarized reflected energy in the time domain, and by using signal processing methods and apparatus to improve the reliability of the detection process. This technique which relies on differences between levels of different polarized reflected energy is difficult and potentially costly to implement.
Information at http://www.nlectc.org/virlib/InfoDetail.asp?intinfoID=201 and http://www.rl.af.mil/div/IFB/tefchtrans/datasheets/CWD-LPR.html, indicates that Lockheed Martin, under contract to the Air Force Research Laboratories and the National Institute of Justice, is in the process of developing a dual-mode (millimeter wave/infrared) camera to detect weapons concealed on an individual. The information indicates that the system will operate at a range of 10 to 40 feet, without the control or cooperation of the individual under surveillance. The described system develops images from the returned Radar energy. The image information is processed using algorithms to automatically detect and recognize concealed weapons. The detection and position information from the Radar sensor would be linked to a second sensor IR or visual camera to display the subject to authorities.
In addition to the above discussed detection systems, there are several new initiatives being pursued under the auspices of the Small Business Innovation Research (SBIR) program in the Concealed Weapons Detection arena. The DARPA SBIR, Topic SB022-033 entitled Personnel and Vehicular Monitoring and Tracking at a Distance seeks to “develop 3D biometric technologies as part of a multi-modal system to detect, track and recognize humans . . . at a distance to support early warning, force protection, and operations against terrorist, criminal and other human based threats.” The particular focus of this work is 3D imaging. The Army Research Office (ARO) SBIR Topic A02-061, Terahertz Interferometric Imaging Systems (TIIS) for Detection of Weapons and Explosives seeks to “develop and demonstrate a terahertz-frequency imaging array with sufficient spatial and spectral resolution to enable the rapid and effective detection of concealed weapons and explosives. The envisioned sensing system will provide real-time imaging with adequate sensitivity for the short-range remote interrogation of objects and persons that might be concealing either weapons or explosives” with a parallel focus on collecting “signature information for a set of expected targets and concealment materials.” The Army Research Lab (ARL) SBIR, Topic A02-037, Explosive Detection System, is focused on chemical signatures of explosives. Such development programs further highlight the need for improved concealed weapon detection systems. The Air Force SBIR, Topic AF03-123 entitled Hidden Threat Detection Techniques seeks to “capitalize on emerging non-contact nondestructive evaluation detection techniques as well as revolutionary concepts for sensors and detectors and tailor them to specific applications for personnel protection.”
In view of the above discussion, it is apparent that there is a need for new or improved systems and methods for rapidly evaluating the threat potential of an individual amongst other individuals at a relatively long distance both indoors and outdoors. It is desirable that at least some systems or methods be capable of being implemented without the need for complex signal processing thereby reducing implementation costs relative to many of the known systems. It is also desirable that the methods and/or apparatus provide an integrated, threat-driven solution to the threat detection problem discussed above.